ADD I T I V E S & T RE ATME N T S
hydrocarbon fuel probably needs to be used at a higher dose rate” with B5 or higher blends, he said. Fuel Management Services literature states that as the percent-
age of biofuel grows its properties as a solvent become “excellent.” Clean tanks and lines and an effective organic dispersant go a long way to minimizing fouling of fuel metering systems by insoluble particulates, the supplier said. But the most significant concern is the impact of cold weather
on biofuels, Fuel Management Services’ literature noted. Biodiesel has a higher pour point than diesel and heating oil. As the per- centage of biodiesel increases so do the pour point, cold flow plugging point (CFPP), and cloud point, the company pointed out; testing for cold weather operability is one way to minimize surprises, it advised. Fuels can be treated to bring them into the desired operability range, the company said. More change seems to be in the offing for blending biofuel
and conventional heating oil. ASTM International discussed a proposed specification for B6 through B20 heating oil at its meeting in June, said Dave Slade, technical services director for Renewable Energy Group (REG), a B100 producer based in Albert Lea, Minn. The proposed specification could be balloted in September, said Slade, who serves on two of ASTM’s committees, including
the one overseeing heating oil. Slade said the proposed spec could be adopted within two years of balloting. Currently the ASTM spec equates B5 with conventional heating oil. REG makes B100 from natural fats, oils and greases. It has
more than 210 million gallons of owned/operated annual pro- duction capacity at biorefineries across the country. The B100 is usually treated for stability prior to blending, Slade said, “and that should carry on and provide good protection in the petroleum fuel as well,” though he said fuel oil dealers might be inclined to use additives to increase stability further. Biodiesel is an oxygenated fuel, meaning its molecules contain
oxygen, Slade noted. For that reason, he said, it does have a little more affinity for water – if water gets into the tank. That happens when condensation occurs in the head space as air is drawn into the tank, as fine cracks let in water, or simply from humidity, Slade said. “The moisture source is always the environment,” he said.
“Biodiesel itself doesn’t bring in any more water, but if you do get water in a tank biodiesel typically will hold a little bit more water in solution. That means you don’t get a water layer in the bottom as quickly.” And that means it takes longer to detect the water, he said. But at a blended level of B5 the tendency of the fuel to hold water is “really not significant,” he said. l FON
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AUGUST 2011 | FUEL OIL NEWS | www.fueloilnews.com
